On the Christian Faith (De fide)

The errors of the Arians are mentioned in the Nicene Definition of the Faith, to prevent their deceiving anybody. These errors are recited, together with the anathema pronounced against them, which is said to have been not only pronounced at Nicæa, but also twice renewed at Ariminum.

118. Christ, therefore, is “God of God, Light of Light, very God of very God; begotten of the Father, not made; of one substance with the Father.”

119. So, indeed, following the guidance of the Scriptures, our fathers declared, holding, moreover, that impious doctrines should be included in the record of their decrees, in order that the unbelief of Arius should discover itself, and not, as it were, mask itself with dye or face-paint. For they give a false colour to their thoughts who dare not unfold them openly. After the manner of the censor's rolls, then, the Arian heresy is not discovered by name, but marked out by the condemnation pronounced, in order that he who is curious and eager to hear it should be preserved from falling by knowing that it is condemned already, before he hears, it set forth to the end that he should believe.

120. “Those,” runs the decree, “who say that there was a time when the Son of God was not, and that before He was born He was not, and who say that he was made out of nothing, or is of another substance or οὐσια, or that He is capable of changing, or that with Him is any shadow of turning—them the Catholic and Apostolic Church declares accursed.”

121. Your sacred Majesty has agreed that they who utter such doctrines are rightly condemned. It was of no determination by man, of no human counsel, that three hundred and eighteen bishops met, as I showed above more at length, in Council, but that in their number the Lord Jesus might prove, by the sign of His Name and Passion, that He was in the midst, where His own were gathered together. In the number of three hundred was the sign of His Cross, in that of eighteen was the sign of the Name Jesus.

122. This also was the teaching of the First Confession in the Council of Ariminum, and of the Second Correction, after that Council. Of the Confession, the letter sent to the Emperor Constantine bears witness, and the Council that followed declares the Correction.